The present invention relates to a mobile unit remote control apparatus, in particular a mobile unit remote control apparatus for remotely controlling the instruments of an automobile or other mobile unit.
Conventionally, there is a so-called smart entry system, in which the doors of a vehicle are locked and unlocked, as the case may be, simply by bringing a portable, compact, wireless device into proximity with the vehicle and removing the device from the vicinity of the vehicle, respectively. Japanese Laid-Open Patent Application No. 5-156851, for example, discloses a vehicle wireless door lock control apparatus comprising a transmitter-receiver unit installed on the vehicle that intermittently emits a radio frequency for the portable unit search and a portable unit that transmits return transmission electromagnetic waves having a predetermined code once it receives this search wave, unlocking the doors when the transmitter-receiver unit determines that the transmission wave code matches a specified code.
The conventional smart entry system also carries a wireless system for locking and unlocking the vehicle doors by operating-existing buttons, in preparation for those times in which the,predetermined code of the transmission wave transmitted from the portable unit cannot be matched with the specified code at the transmitter-receiver unit. For this reason the portable unit can be made to carry a wireless system switch. In this case, however, there is a possibility that the smart entry system and wireless entry system may compete with each other, and it was not made clear which of the two systemsxe2x80x94the smart entry system or the wireless systemxe2x80x94was given priority over the other.
Usually, the portable unit of a smart entry system receives a transmission request signal and proceeds to detect the vehicle, so in terms of battery capacity it consumed a not inconsiderable amount of power. When both systems were operated using a single power source the power consumption of the portable unit not only drained the battery to the point where not only the smart entry system no longer functioned but also the wireless system did not function, either.
Moreover, in order to decrease power consumption the portable unit receiver had to be made simple, which sometimes meant that in strong electrical fields or other areas subject to interference the portable unit mistook this electromagnetic activity for search waves and continued to erroneously transmit return waves. Areas subject to interference include the strong electrical fields near high-voltage power transmission lines and microwave emission sources such as microwave ovens and certain medical equipment. These erroneous transmissions further increased the speed with which the battery was drained of power by the portable unit.
In response to this problem systems have been created that differentiate the frequency band of the search wave from that of the return wave transmitted from the portable unit so as to provide a transmitter-receiver unit with a high degree of frequency selectivity in contrast to the low degree of frequency selectivity of the portable unit, such that when the portable unit comes within a predetermined distance from the vehicle the portable unit transmits an answering signal in response to a questioning signal from the transmitter-receiver unit to release the door lock. However, in areas subject to interference, once the portable unit comes within a predetermined distance from the transmitter-receiver unit an answering signal is transmitted from the portable unit even if no questioning signal has been transmitted from the transmitter-receiver unit, with the danger that the vehicle door will be unlocked against the volition of the user.
It is a general object of the present invention to provide a mobile unit remote control apparatus that prevents competition between the smart entry system and the wireless system by assigning priority to one or the other system.
It is another object of the present invention to provide a mobile unit remote control apparatus that can minimize unnecessary power consumption by the portable unit by halting the transmission of an answering signal after a predetermined period of time when continuously receiving a transmission request signal or a signal similar thereto.
It is another object of the present invention to provide a mobile unit remote control apparatus that can operate a wireless system even if the smart entry system no longer functions due to drainage of battery power, by assigning priority to one or the other of either a smart entry system power supply or a wireless system power supply.
In order to achieve the objects described above, one aspect of the present invention provides a mobile unit remote control apparatus comprising:
a transmitter for transmitting transmission request signals mounted on the mobile unit;
a receiver mounted on the mobile unit for receiving recognition signals transmitted from a portable unit;
an instrument control circuit mounted on the mobile unit for controlling instruments installed on the mobile unit in response to a recognition signal received by the receiver;
a response circuit mounted on the portable unit for transmitting a recognition signal in response to a transmission request signal transmitted from the transmitter unit; and
an operation circuit mounted on the portable unit for transmitting a recognition signal in response to an operation input from an external source, unrelated to the transmission request,
characterized in that priority rankings are assigned to the transmission of the recognition signal by the response circuit and the transmission of the recognition signal by the operation circuit.
By assigning priority rankings to the transmission of the recognition signal by the returning means and the transmission of the recognition signal by the user operating means in this manner, competition between the smart entry system and the wireless system can be prevented.
In the invention described above, the transmission of the recognition signal by the operation circuit may be given a higher priority than the transmission of the recognition signal by the response circuit. By doing so, the wireless system is given priority over the smart entry system and control reflecting the volition of the user can be carried out.
Also, operation of the receiver installed on the mobile unit may be commenced before operation of a transmitter. By doing so, the transmission of the recognition signal by the operating means is given priority and wireless system control can be given priority over smart entry system control.
A separate aspect of the present invention provides a mobile unit remote control apparatus comprising:
a transmitter for transmitting transmission request signals mounted on the mobile unit;
a receiver mounted on the mobile unit for receiving recognition signal transmitted from the portable unit;
an instrument control circuit mounted on the mobile unit for controlling instruments installed on the mobile unit in response to a recognition signal received by the receiver; and
a response circuit mounted on the portable unit for transmitting a recognition signal in response to a transmission request signal transmitted from the transmitter unit,
characterized in that a halting means is provided on the portable unit for halting the transmission of a recognition signal after a predetermined period of time based on a trigger signal indicating that the transmission request signal has been received when such trigger signal is continuously generated.
According to the invention described above, unnecessary power consumption due to erroneous transmission of a recognition signal when the portable unit has erroneously detected a transmission request signal can be kept to a predetermined period of time, thus minimizing portable unit power consumption.
Another aspect of the present invention provides a mobile unit remote control apparatus comprising:
a transmitter for transmitting transmission request signals mounted on the mobile unit;
a receiver mounted on the mobile unit for receiving recognition signals transmitted from the portable unit;
an instrument control circuit mounted on the mobile unit for controlling instruments installed on the mobile unit in response to a recognition signal received by the receiver;
a response circuit mounted on the portable unit for transmitting a recognition signal in response to a transmission request signal transmitted from the transmitter unit; and
an operation circuit mounted on the portable unit for transmitting a recognition signal in response to an operation input from an external source, unrelated to the transmission request,
characterized in that the mobile unit remote control apparatus has a first power supply for supplying power to the response circuit and a second power supply for supplying power to the operation circuit, said second power supply being independent of the first power supply.
According to the invention described above, the wireless system can still be operated off the second power supply even if the smart entry system no longer operates because the first power supply has been exhausted. That is, the response circuit of the portable unit is constantly monitoring for receipt of the transmission request signal, which monitoring consumes a comparatively large amount of electrical power; by providing a separate first power supply for supplying power to the response circuit and second power supply for supplying power to the operation circuit, the operation circuit can be operated off the second power supply even if the first power supply is exhausted.
In addition, according to a separate aspect of the present invention, the mobile unit remote control apparatus may be provided with a common power supply for supplying power to the response circuit and the operation circuit, and a power supply interrupting means for interrupting the supply of power to the response circuit.
By doing so, the supply of power to the returning means can be halted when the smart entry system is not being used, thereby minimizing drainage of the common power supply and making it possible to continue to use the wireless system. Moreover, wireless system control can be assigned priority over smart entry system control. The power supply interrupting means may comprise a switch provided between the common power supply and the response circuit.
In addition, the power supply interrupting means may comprise a breaker circuit that interrupts the supply of power to said response circuit when the current capacity of the common power supply falls short of a predetermined value. By doing so, when the current capacity of the common power supply is below a predetermined value the supply of power to the returning means can be interrupted. Therefore operation of the smart entry system can be halted when the common power supply drains and the current capacity decreases, making it possible to minimize further drainage of the common power supply.
In addition, the power supply interrupting means may comprise a breaker circuit that interrupts the supply of power to the response circuit when the recognition signal from the portable unit is not transmitted for a predetermined period of time. By doing so, when the recognition signal from the portable unit is not transmitted after exceeding a predetermined period of time the unit perceives this as an indication that the user is not in the vicinity of the mobile unit, interrupts the supply of power to the returning means and halts operation of the smart entry system, thereby making it possible to minimize drainage of the power supply.
In addition, the instrument control means of the mobile unit remote control apparatus of the present invention may also be used to control the door locks of the mobile unit. By doing so, the doors of the mobile unit can be locked and unlocked.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.